There has been an ongoing effort to verify the nature of cerebrovascular innervation and the effects these nerves produce. Four putative transmitters have been definitely shown to be present in the wall of cerebral blood vessels: norepinephrine, acetylcholine, substance P and vasoactive intestinal peptide. We propose to continue to expand our inquiry into the role of these transmitters using a variety of histochemical, in vitro and biochemical techniques. The specific aims of this proposal are: 1. Localize each transmitter using immunohistochemistry at the light and electron microscopic levels. 2. Investigate the source of nerves and the possibility of cotransmission by selective destruction of specific types of nerves either surgically or chemically. 3. Verify the activity of nerves and test for the possibility of corelease of transmitters by measuring transmitter release in vitro. 4. Characterize and localize receptors for these transmitters using radioligand binding techniques and light microscopic autoradiography. 5. Investigate the functional role of these transmitters by measuring contractile response and amino acid transport in vitro before and after selective neuronal destruction. This multifaceted approach allows us to first verify the effectiveness and specificity of surgical or chemical nerve destruction. This will be followed by tests of blood vessel function, both smooth muscle contraction and amino acid uptake. Establishment of reliable methods for destruction of nerves will also make it possible to further investigate the role of these nerves using in vivo methods. Increased knowledge of both sensory and motor innervation and exploration of possible functional interrelationships between different kinds of nerves may provide understanding of the pathogenesis of cerebrovascular disorders, such as stroke, headache and the sequelae of cerebral trauma, as well as suggest new approaches for therapy.